1. Technical Field
The present invention relates to an apparatus for fabricating a flat panel display device and, more particularly, to a glass support pin for use with fabrication of a liquid crystal display (LCD) device.
2. Description of Related Art
Fabrication of LCD devices involves many unit processes at factory facilities. Each unit process performs a different operation required for fabricating LCD devices. LCD fabrication process may involve delivery of a glass substrate where an LCD device is mounted. Many unit processes are automated and rely on a robot. In particular, a transfer robot may deliver the glass substrate from one unit process facility to a different unit process facility.
An aligning unit performs an aligning process of the LCD glass substrate before the LCD glass substrate is kept in storage in the cassette or before the LCD glass substrate is loaded to the different facility. The aligning unit includes glass support pins supporting the LCD glass substrate and an aligning member that aligns the LCD glass substrate. During the aligning process, the aligning member moves the LCD glass substrate to an alignment position by using the glass support pins. Frictional contact may occur between the LCD glass substrate and the glass support pins. Frictional contact may cause scratches or cracks on the surface of the LCD glass substrate.
The LCD glass substrate typically has a thickness of about 0.7 mm to 2.2 mm, which is substantially smaller than its length and width. Because the LCD glass substrate is so thin and large, it may not be highly resistant to an external impact and sagging phenomenon. The sagging phenomenon may occur from severe bending caused by self-weight of the LCD glass substrate. Additionally, as an LCD panel becomes larger in size, the crack occurrence rate may increase upon lifting of the glass substrate with the glass support pins. Further, a wet liquid coating film such as a photoresist film may flow down to generate blurs. The coating film may be formed with uneven thickness.
FIGS. 1A and 1B are a plan view and a cross sectional view showing an arrangement of glass support pins 22 and a carrier plate 5 according to the related art. Referring to FIGS. 1A and 1B, the carrier plate 5 comprises a chuck 21 and the glass support pins 22. The glass support pins 22 support a glass substrate 10. A robot arm transports the glass substrate 10 and puts it on the chuck 21. The glass substrate 10 is then vacuum-absorbed onto the surface of the chuck 21. Subsequently, the surface of the glass substrate 10 is coated with the photoresist film using equipment such as a photoresist coater.
The glass support pins 22 are lifted from the chuck 21 to support the glass substrate 10 until the transfer robot takes off the glass substrate 10 from the chuck 21. The glass support pins 22 are typically arranged at intervals of 340 mm in width and 365 mm in length, and total 36 glass support pins 22 support weight of the glass substrate 10 in FIG. 1A. A load applied to each support pin may be substantial. The transfer robot transfers the glass substrate 10 to a facility for a next process. The robot arm is moved toward a bottom surface of the glass substrate 10 between the glass support pins 22 and the chuck 21, as shown in FIG. 1B.
FIG. 2 further illustrates the glass support pins 22 in detail according to the related art. Reference character ‘L’ denotes the length of the large glass substrate 10, and ‘d’ denotes the distance between the glass support pins 22. Each glass support pin includes a body 22a and a tip 22b formed on the top of the body 22a. Referring to FIG. 2, a height difference exists between portions P1 and portions P2. The portions P1 are not supported by the glass support pins 22 on the chuck 21 and the portions P2 are supported by the glass support pins 22 on the chuck 21. This difference may result from the weight of the large glass substrate 10. The portions P1 may bend in the glass substrate 10, which may lead to crack on the rear surface of the glass substrate 10. Accordingly, there is a need for a glass support pin and a carrier plate that overcome drawbacks of the related art.